This part of ISO 5751 gives guidelines for the design of, and specifies the designation and calculation of the dimensions for metric series motorcycle tyres. It is applicable to motorcycle tyres with a reduced height/width ratio (100 and lower) that can be fitted on cylindrical bead-seat or 5° tapered bead-seat rims. It is also applicable to other concepts of tyre and rim, provided the appropriate rim/section ratios and coefficients are established for them.